import Foundation

public class ListNode {
  public var val: Int
  public var next: ListNode?
  public init() { self.val = 0; self.next = nil; }
  public init(_ val: Int) { self.val = val; self.next = nil; }
  public init(_ val: Int, _ next: ListNode?) { self.val = val; self.next = next; }
}
